Feeding means for feeding solid fuel from a storage silo or equivalent into a solid fuel heating boiler

ABSTRACT

The invention concerns an apparatus for feeding solid fuel from a storage silo or equivalent to a solid fuel-using heating boiler. The feeding apparatus comprises a piston, which has been disposed to carry out a reciprocating motion within a tube which through an aperture communicates with the solid fuel storage silo or equivalent, and which communicates by its other end with the heating boiler. With a view to accomplishing the feeding of the solid fuel with reliable certainty, before the piston, in the feeding apparatus of the invention there has been provided in the lower part of the storage silo or equivalent, a rotatably disposed vane.

BACKGROUND OF THE INVENTION

The present invention concerns a feeding means serving to feed into asolid fuel-using heating boiler, solid fuel from a storage silo orequivalent, said feeding means comprising a piston means disposed tomove reciprocatingly in a tube means communicating by an aperture withthe solid fuel storage silo or equivalent and communicating by its otherend with the heating boiler.

As a consequence of the continuous increase in price of oil, the use ofsolid fuel, such as wood chips, peat etc., is increasing at anaccelerating rate in heating energy generation. Several different typesof chipping machines for chip production are known. The operation ofconventional chippers is based on a rotating drum-like roll which servesas blade and against which the wood is radially fed by the aid ofseparate feeding means. Such chippers require a high power input,whereby the producing of chips involves comparatively high expenditure.

It has been found that larger sized chips, or so-called lump chips, arebetter suited owing to their properties to be used towards heatproduction, compared with the above-mentioned common chips. To thepurpose of lump chip producing, a lump chipper has been disclosed in theFinnish patent application No. 791491, comprising a rotating, conicalscrew. The helical surface of this screw acts as cutting blade and itprovides the feeding of the wood, in addition to the chipping operation.

One advantage which lump chips have over conventional chips is that whenstored in a heap, lump chips dry out because the air is able to passthrough between the lump-shaped wood pieces. In contrast, conventionalchips are too closely packed, whereby the burning of the wet chips in aboiler causes difficulties and extra costs, in addition to which the wetchips have a low calorific value.

At present, the feeding of lump chips into a heating boiler isaccomplished by manual labour in that lump chips are shoveled into thefurnace of the boiler as required. Quite obviously this problem solutionis not satisfactory. In addition, the shovelling done as human labour israther strenuous work.

Attempts have been made to find an appropriate apparatus solution forthe feeding of lump chips, but these attempts have not met with anysuccess so far. One has tried to use for the feeding of lump chips, ascrew conveyor (as has been disclosed e.g. in the German publicizingprint No. 2 821 767), but a feeding means of this type does notconstitute any satisfactory solution.

Solid fuel has been fed from a storage silo or equivalent into a solidfuel-using heating boiler with the aid of so-called piston feedingmeans. Such a feeding means is disclosed e.g. in the Finnish Pat. No.40187, in the Swedish Pat. No. 32.806 and in the German Pat. No. 74.080.This piston means of prior art comprises a piston in reciprocatingmotion, fitted into a passage which through an aperture communicateswith a solid fuel storage silo or equivalent. The drawback encumberingthese piston feeding means of prior art is that the solid fuel cannot bemade with positive reliability to go from the storage silo or equivalentbefore the piston of the piston feeding means, owing to the vaultingtendency of the solid fuel.

SUMMARY OF THE INVENTION

The object of the invention is to provide a solid fuel feeding means bythe aid of which solid fuel can be fed into a heating boilercontinuously and in a way which is reliable in operation. Still anotherobject of the invention is to provide a feeding means enabling theoperation of the heating boiler to be automated with regard to theconsumption of solid fuel. It is furthermore an object of the inventionto provide a feeding means making sure of a long enough automaticoperating period for heating boilers.

The objects of the invention are achieved by a solid fuel feeding meanswhich is mainly characterized in that with a view to boosting therunning of the solid fuel from the storage silo or equivalent through anaperture before the piston means enclosed in a tube means, there hasbeen rotatably disposed a vane means in the lower part of the storagesilo or equivalent.

With the feeding means of the invention numerous significant advantagesare gained. First, the feeding means of the invention enables solid fuelto be continuously automatically fed into the heating boiler, in amanner which is absolutely reliable in operation. The feeding means ofthe invention also renders possible easy automation of the heatingboiler with regard to its solid consumption. Moreover, thanks to thefeeding means of the invention the heating boiler may operate duringcomparatively long periods under automatic control.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail with reference to advantageousembodiments of the invention, presented in the figures of the attacheddrawings, but to which the invention is not meant to be exclusivelyconfined.

FIG. 1 shows an advantageous embodiment of the feeding means of theinvention, in top view.

FIG. 2 shows the feeding means of FIG. 1, in elevational view.

FIG. 3 shows, in elevational view, an advantageous embodiment of thevane means rotatably disposed in the lower part of the storage silo orequivalent belonging to the feeding means of the invention.

FIG. 4 shows the vane means of FIG. 3, in top view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the embodiment of FIGS. 1 and 2, the feeding means of the inventionhas been generally indicated by the reference numeral 10. The feedingmeans 10 comprises a piston means 22 disposed to be reciprocatinglymovable. The piston means 22 has been disposed to carry out itsreciprocating motion in the tube 30, which communicates by the aperture23 with the storage silo 27 valid for solid fuel, e.g. lump chips. Thusfrom the silo 27 through the aperture 23, solid fuel 32 runscontinuously into the tube 30, and the reciprocatingly moving pistonmeans 22 pushes the solid fuel forward in the tube 30. The tube 30communicates by its other end with the heating boiler 31. In order thatthe flow of solid fuel 32 from the silo 27 through the aperture 23before the piston means 22 in the tube 30 might be reliable, there hasbeen rotatably disposed in the lower part of the silo 27, a vane means28. The rotation of the vane means 28 within the silo 27 is preferablysynchronized with the reciprocating motion of the piston means 22 asdescribed later on. The edge 22a of the piston means is preferably madeto have a V shape, whereby the piston means will efficiently push thesolid fuel 32 forward in the tube 30. The upper margin 24 of theaperture 23 has been shaped to constitute a sharp cutting edge operatingas counterblade and causing reliable chopping of the solid fuel 32 atthe aperture 23, with the result that no occlusion will occur in thefeeding of the solid fuel 32 in the tube 30, particularly not at theaperture 23.

In the embodiment of FIGS. 1 and 2 the motion of the piston means 22 hasbeen accomplished by means of the following mechanism. A motor, forinstance an electric motor, 11 has been disposed to drive over aneccentric cam 12a mounted on a shaft 12 and over a lever arm 13 and aconnecting rod 15, and the pawl 16. The pawl 16 rotates the ratchetwheel 18, which carries a great number of teeth 19. The rotation of theratchet wheel 18 has been delimited by means of a locking pawl 17. Therotational movement of the ratchet wheel 18 is transmitted by theconnecting rod 20 to the piston means 22, whereby the piston means 22performs a reciprocating motion. The reference numeral 21 indicates thebearing of the connecting rod 20. Reference numerals 25 and 26 indicatebearing arrangements which are necessary.

While the movement of the connecting rod 20 produces the reciprocatingmotion of the piston means 22, the movement of the connecting rod 20 atthe same time causes rotary movement of the vane means 28 in such mannerthat the vane means 28 has run over the aperture 23 when the pistonmeans is in its rear position, in the so-called rear deadpoint position.

In the storage silo 27 for solid fuel 32 there has been preferablydisposed, upon the hub of the vane means 28 and pivotally attached, amixing arm 29, by the aid of which any solid fuel 32 that may adhere tothe walls of the silo 27 can be dropped into the lower part of the silo27.

In the embodiment of FIGS. 3 and 4, the vane means 28 comprises the vaneparts 28a and 28b. The vane part 28a is rigid and has been disposed torotate about the shaft 36. The rigid vane part 28a may therefore bendelastically at its root only. The other vane part 28b has been connectedto the rigid vane part 28a by the aid of a hinge means 33, whereby theother vane part 28b is free to turn about the hinge means 33. The hingeaxle of the hinge means 33 is substantially parallel to the longitudinalaxis of the rigid vane part 28a, i.e., the hinge axle of the hinge means33 is radially oriented.

By the vane means of FIGS. 3 and 4, the advantage is gained that if suchchips have accumulated on the rim of the aperture 23 which have not yetgone through the aperture 23 into the tube means 30, the hinged vanepart 28b of the vane means 28 can fall down immediately after passingthe aperture 23, whereby on the next stroke of the vane means 28, thevane means 28 will efficiently push the chips forward towards theaperture 23. When the vane means 28 in the course of its stroke hitsagainst the chip heap on the margin of the aperture 23, the hinged vanepart 28b of the vane means 28 is naturally free to rise upwardly, butthe rigid vane part 28a of the vane means 28 instead remains in itshorizontal plane. A vane means 28 of this kind therefore ensures thereliable operation of the feeding means 10, and chips in sufficientquantity are all the time delivered before the piston means 22 of thefeeding means 10.

As shown in FIGS. 3 and 4, there has preferably further to the hingedvane part 28b of the vane means 28 been affixed a sleeve-like member 34,to which in its turn has been attached a flexible, whip-resemblingmember 35 advantageously. The whip-like member 35 consists of a flexiblesteel wire. A vane means 28 provided with such a whip-like member 35 atthe same time causes any solid fuel 32 that may adhere to the walls ofthe silo 27 to fall down into the lower part of the silo, whereby in anembodiment of this type the mixing arm 29 is superfluous.

The tube means 30 conducting the solid fuel 32 to the heating boiler 31is advantageously composed of a plurality of tubular parts joinedtogether. It should be particularly noted that the second tubularsection has a larger diameter than the first tubular section, andsimilarly the diameter of the third tubular section exceeds that of thesecond tubular section, and so on. A widening tube means 30 of this kindreliably counteracts the tendency of the solid fuel 32 to travel back inthe tube 30. The tube means 30 is advantageously an elastic tube means,whereby the feeding means of the invention 10, and similarly the tubemeans 30, may be mounted in any desired position with reference to theheating boiler 31. Likewise, the elastic tubular design affords easy andsimple length adjustability of the tube means 30. As material for thetube means one may use steel, or equally well plastic or anotherequivalent material.

In the foregoing only the principle solution of the invention has beenpresented, and one advantageous embodiment thereof. It is obvious to aperson skilled in the art that the invention may be modified in numerousdifferent ways within the scope of the inventive idea expressed in theclaims following below.

We claim:
 1. Feeding means for feeding solid fuel from a storage silo toa heating boiler, said feeding means comprisingpiston means adapted tomove reciprocatingly, tube means communicating with the heating boilerand in which said piston means is disposed, aperture means communicatingsaid tube means with the storage silo, vane means rotatably disposedwithin a lower portion of the storage silo to effectuate delivery of thesolid fuel from the storage silo to the boiler through said tube means,said vane means comprising a substantially rigid portion, and a turnableportion, and hinge means for interconnecting said turnable andsubstantially rigid portions of said vane means, said hinge meanscomprising a hinge axle substantially parallel with a longitudinal axisof said substantially rigid portion of said vane means.
 2. The feedingmeans of claim 1, further comprisinga flexible, whip-like memberattached to said turnable portion of said vane means.
 3. The feedingmeans of claim 2, whereinsaid flexible, whip-like member is in the formof a steel wire, and further comprising a sleeve-like member affixingsaid whip-like member to said turnable portion of said vane means. 4.The feeding means of claim 1, whereinrotary movement of said vane meansinside the storage silo being synchronized with the reciprocating motionof said piston means.
 5. The feeding means of claim 1, furthercomprisingan edge of said piston means being substantially V-shaped. 6.The feeding means of claim 1, further comprisingan upper rim of saidaperture means being shaped to constitute a sharp cutting edge.
 7. Thefeeding means of claim 1, the improvement further comprisinggeneratingmeans for generating the reciprocating motion of said piston means, saidgenerating means comprising drive means, pawl means, transmission meansdisposed such that said drive means drives said pawl means through saidtransmission means, a ratchet wheel disposed such that said pawl meansdrives the same, and a connecting rod interconnecting said ratchet wheeland said piston means, such that rotary motion of said ratchet wheel istransmitted through said connecting rod to said piston means.
 8. Thefeeding means of claim 7, whereinsaid transmission means comprises ashaft engaged with said drive means, a lever arm engaged with saidshaft, and a connecting rod engaged with said lever arm and with saidpawl means.
 9. The feeding means of claim 7, further comprisinglockingpawl means for engaging and limiting rotation of said ratchet wheel. 10.The feeding means of claim 1, further comprisinga mixing arm disposedwithin the storage silo for dropping any solid fuel that may adhere tothe wall of the storage silo.
 11. The feeding means of claim 1,whereinsaid tube means leading to the heating boiler comprises aplurality of tubular portions interconnected with one another such thatin the direction towards the heating boiler, a subsequent tubularportion has a larger diameter than a preceding, adjacent tubularportion.
 12. The feeding means of claim 11, whereinsaid tube means iselastic.